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Drawings by dffhrtcv3

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									Drawings
        The Drawing Set
Design Drawings
   System Block Diagram
   Circuit Design Sketch
   Packaging Plan
Working Schematic
Breadboard Drawing
PC Board Design Layout
PC Board Artwork
                            Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 76)
 The Drawing Set               (Continued)


PC Board Fabrication Drawing
PC Assembly Drawing
Sheet Metal Drawing
Wiring Diagram
Final Packaging Drawing



                     Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 76)
The Design Drawings
System Block Diagram




             Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 60)
Circuit Design Sketch




              Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 61)
Packing Plan




         Electronic Project Design and Fabrication 4th edition, Ronald Reis ( page 61)
Introduction to Schematics
       ANSI and IEEE
Define accepted practices and symbols
for schematic and electrical diagrams.
Most CAD program conform to these
standards.

Schematic symbols are covered by
(ANSI Y32.2)
Standard Symbols
                Designators
  Resistor - R                  Capacitor – C
  Switch - S                    Diode – D
  Transformer – T               Fuse – F
  Transistor - Q                Relay – K
  IC – U                        Coil/Inductor – L
  Crystal – Y                   Microphone – MK

Protel places the proper designator on all parts for you.
  Layout Considerations
If a schematic is large, split the
schematic into functional sections, each
on a separate page, making sure to
properly label connection ports.

Layout should be arrange to develop
from the top to bottom and from left to
right as the signal flows
Layout Considerations (continued)
 Voltages should be clearly marked.

 Ground symbols should always be
 drawn below the line.
  Proper Signal Flow Example
INPUTS                       Outputs

          Higher Potential




          Lower Potential
Layout Considerations (continued)
 All connecting lines are either vertical or
 horizontal.
    There are a few exceptions:
           Bus connections
           Flip flops
           Bridge Rectifiers
Layout Considerations (continued)
 Similar circuits should be drawn
 uniformly.

 Common circuits should be drawn
 according to accepted conventions.
    Example
Non-Standard Schematic
    Example
Non-Standard Schematic




   Standard Schematic
Layout Considerations (continued)
 When identifying values of resistors,
 capacitors or inductors:
    Use proper unit prefixes
       p for Pico
       u for Micro
       m for milli
       K for Kilo
       M for Mega
    For resistors, ohms is implied and should not be
     used.
Layout Considerations (continued)
 Parts should be numbered starting from
 the upper left hand side of the
 schematic to the lower right hand side.

 This method makes it very easy to
 locate parts on the schematic.
Part Numbering Example
Layout Considerations (continued)
 Short dashed lines indicate mechanical
 interconnects.

 Each schematic should have a filled in
 title block.
Layout Considerations (continued)
 Lines should be drawn with the minimum of
 crossovers and joggles.

 Junctions of 3 or more wires should be
 marked with a dot to indicate a connection.
 No dot, no connection.

 Lines between components should take the
 shortest path.
Example of Crossover and
        Joggles
Connections and Dots
What’s Wrong With This
       Picture?
Improved Schematic

								
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